1. Day 40 – Daily Starter
Consider your understanding of ionic bonding and valence electrons, which side of the periodic table has elements that have a stronger need for gaining electrons?

2. Day 39 Electronegativity “Electron Tug of War” Oxidation Number
Ionic Names
Ionic Formulas

4. Electronegativity
It is the measure of the attraction an atom has for a shared pair of electrons.
Elements with greater electronegativity have a greater attraction and strength towards electrons
Ex: Fluorine (F) is the MOST electronegative element of all; F will “steal” electrons from any element it bonds with

5. Cl is also very electronegative
Notice how Cl “steals” the electron from Na

6. Forms an ionic compound Forms a molecular compound
A way to look at it…
Ionic Bonds
Covalent Bonds
Metal + Nonmetal
Nonmetal + Nonmetal
Transfer electrons
Share electrons
Forms an ionic compound
Forms a molecular compound

7. Types of bonds
Nonpolar covalent bond – the electrons are shared equally. (pure covalent)
Polar covalent bond – the electrons are not shared equally. The more electronegative atom attracts the electrons more strongly than the less electronegative atom.
Ionic bond – the electrons are not shared at all. This bond is formed by the + and – attraction.

8. Molecule
A molecule is a neutral group of atoms that are held together by covalent bonds.
Molecular elements are elements found in nature as molecules because they are more stable together than alone.
EX: Diatomic Elements (Di = 2)
H2 N2 O2 F2
Cl2 Br2 I2

10. What type of bond will form?
The difference in electronegativity values between bonding atoms will dictate the type of bond formed.
If the electronegativity difference is…
The bond type is…
Greater than 1.7
Ionic
Between or = to
1.7 & 0.5
Polar Covalent
Less than 0.5
Nonpolar Covalent

11. GET YOUR OWN MARKER BOARD!

12. Selfish atoms, the ionic bond
Sodium Chloride (NaCl)
Electronegativity
Na 0.9
Cl 3.0
Electronegativity difference = 2.1
What type of bond is this?

13. Selfish atoms, the ionic bond
Sodium Chloride (NaCl)
Electronegativity
Na 0.9
Cl 3.0
Electronegativity difference = 2.1
What type of bond is this?
IONIC (greater than 1.7)

14. What’s mine is yours… the covalent bond
Carbon Monoxide (CO)
Electronegativity
C 2.5
O 3.5
Electronegativity difference = 1.0
What type of covalent bond is this?

15. What’s mine is yours… the covalent bond
Carbon Monoxide (CO)
Electronegativity
C 2.5
O 3.5
Electronegativity difference = 1.0
What type of bond is this?
Polar Covalent (between 1.7 and 0.5)

16. When in Doubt…
A metal (cation +) and a nonmetal (anion -) will form an ionic bond
From opposite sides of the periodic table
Two nonmetals will form a covalent bond

17. Now you try… Marker Boards
Work with a partner and write your answer so I can see it if you are called on…
Write the values for each element, the difference for each bond, and the type of bond that will be formed.
Li and H

18. Now you try… Marker Boards
Work with your assigned unit partner and write your answer so I can see it if you are called on…
Write the values for each element, the difference for each bond, and the type of bond that will be formed.
H2O

19. Remember….
You are finding the difference for EACH bond in a molecule or compound H2O
this bond =3.5 – 2.1 = 1.4
And this bond =1.4(polar covalent)

20. Now you try… Marker Boards
Work with a partner and write your answer so I can see it if you are called on…
Write the values for each element, the difference for each bond, and the type of bond that will be formed.
CO2

21. Now you try… Marker Boards
Work with a partner and write your answer so I can see it if you are called on…
Write the values for each element, the difference for each bond, and the type of bond that will be formed.
NH3 (ammonia)

22. Now you try… Marker Boards
Work with a partner and write your answer so I can see it if you are called on…
Write the values for each element, the difference for each bond, and the type of bond that will be formed.
NO (nitric oxide)

23. HOMEWORK
Electronegativity Worksheet
Due Next Class